North Carolina’s environment agency said Friday it will alter permits for Duke Energy’s Riverbend power plant, west of Charlotte, and two other plants to end illegal coal ash discharges.

The state’s announcement parallels steps Duke said earlier this week it would take – even though the N.C. Department of Environment and Natural Resources had blasted the plan Thursday as inadequate. And the state action might not stop contaminated water seeping from Riverbend’s ash pond dams.

Environmental advocates depicted the announcement as proof Duke and DENR are collaborating to avoid cleaning up all 33 of Duke’s North Carolina ash ponds.

DENR said the permit changes could force Duke to remove the ash from Riverbend’s ponds on the shores of Mountain Island Lake.

Duke had already said Thursday that it plans to move the 2.7 million tons of ash at Riverbend within 4 1/2 years, taking it to Charlotte’s airport.

Duke had no comment on the DENR announcement, referring to its ash plan released Thursday.

The permits DENR will modify allow the Riverbend and Asheville plants to drain wastewater from their ash ponds. Permit modifications would force a third plant, Sutton in Wilmington, to accelerate closing its ponds.

DENR said the permit changes would “eliminate all unauthorized discharges” at Riverbend and Asheville.

“Unauthorized” means all wastewater or stormwater draining from the plant that isn’t allowed under the plant’s discharge permit, DENR spokesmen said.

Duke would have to stop dam seeps if those contaminants, added to pollutants already allowed by the permit, break permit limits, the spokesmen said. If the addition of those seeps don’t break the permit limits, they would be allowed.

“It will all be driven by the science,” said Drew Elliot, DENR’s communications director.

But some contaminants detected in Riverbend’s seeps, including arsenic, don’t have permit limits. The permits instead require that Duke only monitor levels of arsenic, selenium and mercury, metals found in ash.

Drainage from ash ponds was discussed in internal emails between Duke and DENR that the Southern Environmental Law Center released Thursday.

The negotiations over lawsuits the state had filed against Duke included allowing the drainage to be covered by plant permits. The provision was later part of a proposed settlement agreement between the two that was later sidelined.

DENR is “giving (Duke) retroactive amnesty, a get-out-of-jail card that allows a wastewater treatment facility to spring a leak,” said Frank Holleman, a senior attorney at the law center.

Holleman called Friday’s announcement a delaying action by DENR, claiming it was crafted so the agency would appear aggressive toward Duke. The department could simply seek a court order forcing Duke to remove its ash, he said.

DENR has defended its oversight of Duke, including filing four lawsuits over its coal ash operations.